Best Catalytic Converter Cleaner

Catalytic Converter

When they first appeared in the automotive world in the mid-1970s, catalytic converters seemed a miracle of technology. Environmental regulations were just being introduced. Smog was a major issue in large cities and automobile exhaust was a major factor. Car manufacturers could incorporate a catalytic converter into a vehicle’s exhaust system and the converter’s chemical reaction process would strip out the worst components of the internal combustion engine’s emissions. It also created a market for the catalytic converter cleaner.

Catalytic converters were great because they had no moving parts so they lasted a long time and they only had a limited effect on the engine’s performance. However, they came with two significant downsides. First, exhaust particulates built up inside a converter, gradually constricting and eventually clogging the exhaust system. Second, the metals that made a catalytic converter work (typically palladium or platinum) were expensive, so it cost a lot to replace one. Fortunately, catalytic converter cleaner is now available to extend your converter’s life by cleaning out your exhaust system rather than your wallet.

How We Reviewed

Image via Amazon

Our catalytic converter cleaner review process involved assembling an extensive list of products offered. We focused online, as even the largest chain auto part/supply shops only carry a few inventory items. We narrowed the list by comparing professional reviews and customer review sites. Special consideration was given to reputable brands, pro/con lists from actual users, and especially the long-term effects of using each catalytic converter cleaner on a vehicle’s engine, exhaust system, and the converter itself. Only the seven products that met these criteria made our list.

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Overall Price Range

The prices of items on our list remain in a small range: $ to $ (based on volume). There is a $ large volume item intended for mutliple applications. With this narrow of a price range, it is tempting to suggest buying each until one does the job. However, each product presents different features that set them apart. The best way to determine your price point is to decide first what you actually need.

What We Reviewed

Solder-It (CAT-1) Catalytic Converter Cleaner

41cn4g0Lp L. SL500


Solder-It is both a catalytic converter cleaner and a de-odorizing solution that helps eliminate the sulfur (rotten-egg) smell often produced by catalytic converters. At $15, it is one of the least expensive items we reviewed for this list. It made the list because customers gave it rave reviews. It is also useable on a wide range of engines and a wide range of vehicle years. Besides cars and trucks, it is applicable for all-terrain-vehicles, motorcycles (street, racing, cruisers, and off-road-motorcycles), motor-scooters, snowmobiles, and personal marine craft engines.


  • Relatively inexpensive
  • Safe for use is a wide range of engines and manufacturing years (consult your manual)
  • Helps clean the oxygen sensor in addition to the converter itself


  • Many reviewers noted needing two cans; but not in the same tank of gas
  • Not as long-lasting as other products we reviewed
  • Does not reset manually reset check engine lights

OXICAT – Oxygen Sensor & Catalytic Converter Cleaner

316 LWmKijL. SL500


OXICAT was originally formulated for the European market, which has more stringent emissions regulations than the United States. It is certified to German TUV standards and is safe for gasoline, diesel, and hybrid engine usage. Besides the catalytic converter and oxygen sensor, OXICAT is designed to clean your vehicle’s entire exhaust system, dissolving soot and carbon deposits (with regular use, which is approximately every 5,000 miles).


  • In the lower price bracket on our list
  • Regular use shown to lower car emissions
  • Engineered to higher European requirements


  • Legal statement on the can states outright it cannot fix a broken converter
  • Some cars required more frequent usage than recommended
  • Still will not reset your manual check engine light

CRC 05063 Guaranteed to Pass Emissions Test Formula


Not only is “Guaranteed To Pass Emissions” the least expensive catalytic converter cleaner on our list (at $8), its name also puts its guarantee up front. The company will refund you twice what you paid if you do not pass your emissions test after using it. Of course, this is subject to some conditions, including the fact that it only works if your catalytic converter is merely dirty and not broken. The company claims its formula is the maximum allowable cleaning fluid concentration by US environmental regulations. With regular use (every 3,000 miles) it will super-clean your fuel system in addition to the converter and exhaust.


  • So inexpensive you could make a profit if you claim on the guarantee
  • Is useable with ethanol-blended fuels
  • Customer comments note high success rate with pre-inspection usage


  • Not recommended for diesel use
  • Customer comments urge paying special attention to instructions for real results
  • Guarantee is gimmicky and may be difficult to claim

Red Line (60103) Complete SI-1 Fuel System Cleaner


Red Line wants to make its fuel system/catalytic converter cleaner easy to use. The Amazon page features a vehicle compatibility check system so you can quickly determine this before you buy. The bottle is designed with a built-in funnel spout for no-spill pouring it into your fuel tank. The product cleans fuel injectors, carburetors, valves and combustion chambers with a combination of detergents and oils meant to clean and protect moving parts as well as the exhaust system. It is also safe for continual use and the company recommends regular application to extend engine life.


  • Ease of use
  • Designed for regular use and is least harsh on engine of the products we reviewed
  • Safe for GDI fuel injectors


  • May not be as immediately effective for use just before emissions tests
  • Regular use as recommended (weekly) can get expensive
  • Customers say be cautious when using with high-octane fuels, as this increases it two octane

Royal Purple Max-Clean Fuel System Cleaner and Stabilizer 11722


One of the most popular products on our list, Max-Clean is more than a catalytic converter cleaner. It claims to clean pretty much every part it can reach inside your car, from the fuel lines to the engine and the exhaust system. It made the list because this specifically includes particulate buildup in the exhaust pipes and catalytic converter. The manufacturer claims that Max Clean is tested safe on “the entire spectrum of engines on the road”, including old, new, gasoline, diesel, and even turbocharged. However, we still recommend checking your vehicle’s shop manual. The company also boasts a 3.2% increase in fuel economy and an average of 2.3% horsepower boost after one usage. Also good for rough idle and engine knocking and pinging.


  • A bargain if it does all that is claimed
  • Tested to reduce toxic emissions


  • Consumers say effective pre-emissions test, but other results may vary
  • Regular use can get expensive

Cataclean 120018CAT Cataclean Fuel And Exhaust System Cleaner

41TUV5YI6EL. SL500


In contrast to some of the we-clean-everything positioning of other items on our list, Cataclean is highly focused on just your exhaust, oxygen sensor, and catalytic converter. As its three-liter packaging would indicate, it is intended for long-term treatment (over 30 gallons of gasoline) and it is only for gasoline engines. The manufacturer states that it will reduce carbon buildup throughout your engine and exhaust, restoring your vehicle’s horsepower and power-train output.


  • A specialized product good at doing one job well
  • Manufacturer encourages most effective long-term use with packaging volume
  • Customer reviews say it does what it says


  • Larger container requires a funnel for pouring into the gas tank
  • Restoring horsepower effect is limited in older/high-mileage cars
  • Product narrowly limited for specialized use in only gasoline engines

Cataclean 473ml Engine and Catalytic Converter Cleaning Treatment


This is the second Cataclean product that made our list. This one is focused on engine gasket life extension in addition to internal cleaning. Like the previous product, it cleans carbon build-up from fuel injectors, cylinder heads, oxygen sensors, and your catalytic converter. Unlike the previous product, this one is safe for gasoline, diesel, and hybrid engines. Independent testing showed that Cataclean lowers emissions significantly.

Labeling on this product specifically recommends pre-emissions test usage and that it may extend the life of your oxygen sensors and catalytic converter, as well as the engine. Regular usage (four times a year) is recommended for best results. By volume, this is the most expensive product on our list, but customer testimonials back up its effectiveness. Not only does it do the job on your catalytic converter, it also remedies issues including loss of power, hard starts, knocking, and hesitation.


  • Company is direct about regular, long-term usage for best results
  • Convenient built-in funnel spout for mess-free pouring into the gas tank
  • Made in the USA


  • Most expensive item on our list
  • Recommended regular treatments compound the expense
  • More than most customers need for a one-time, pre-emissions test fix


Garage hacks and Internet discussion groups would have you believe that you can clean a catalytic converter as a do-it-yourself project. Techniques range from running your car in a low gear to high-revving the engine to super heat the converter. Some even recommend doing this while the car is suspended on a garage rack while manning a fire extinguisher just in case. Others suggest banging on the converter with a hammer to dislodge larger particles. However, specially engineered catalytic converter cleaner solutions are widely available and so easy to use, especially when employed as part of your vehicle’s regular maintenance, that these would-be DIY types are better reserved for an hour’s YouTube entertainment.

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1. What Is Catalytic Converter Cleaner?

A catalytic converter cleaner is typically a gasoline additive designed to burn in your engine’s normal combustion process so that it becomes part of your vehicle exhaust and strips deposits from the catalytic converter’s internal surfaces as it heads through the exhaust system.

2. When Is It Best to Use a Catalytic Converter Cleaner?

As your car ages, typically beyond 75,000 miles, it is best to begin using a catalytic converter cleaner on a regular basis. Two of the best places to look for guidance on this are your automobile manufacturer’s service recommendations (easily available online) and the catalytic converter cleaner’s recommendations.

3. What If My Vehicle Is Displaying a “Check Engine” Light or Has Failed an Emissions Test?

Though a check engine light can result from many symptoms besides a clogged catalytic converter (see your vehicle’s manual for details), the relatively low expense of trying a catalytic converter cleaner may be worth trying as a solution to either of these issues.

4. Will a Catalytic Converter Cleaner “Fix” My Catalytic Converter?

Short answer: Maybe. A catalytic converter cleaner can help clear out a converter clogged by the gradual buildup of exhaust soot and particulates on the converter’s internal surfaces. However, it is unlikely to clear out a major clog, particularly if some material has broken off and become lodged inside the converter. There is a point where you will have to replace the converter. However, because of the relatively low cost of catalytic converter cleaners, it may be worth a try to see how much it will improve the situation.

5. Do I Need Any Special Knowledge or Equipment to Use a Catalytic Converter Cleaner?

For the most part, you only need the skill and equipment required to pour a container of catalytic converter cleaner into your vehicle’s gas tank. However, we highly recommend consulting your vehicle’s shop manual and/or consulting a qualified mechanic. Some catalytic converter cleaners exceed vehicle requirements and/or engine tolerances and could cause more damage than good. Additionally, be sure to read the catalytic converter cleaner’s instructions for special handling instructions. Gloves, eye protection, and a spill cleanup kit are highly recommended, as many cleaners contain caustic chemicals that are damaging to skin, eyes, and automobile finishes.

6. Will a Catalytic Converter Cleaner Automatically Reset My Vehicle’s Check Engine Light?

The depends largely on your vehicle. Some vehicles have a designated catalytic converter light. Others have a general check engine light that is connected to more than one engine system. A number of customer reviewers discovered that, though the catalytic converter cleaner fixed the problem, their check engine light required manual resetting. Be sure to consult your vehicle’s shop manual and/or a professional mechanic to learn how this works on your vehicle.

The Verdict

With so many well-regarded and competitively priced products focused on addressing your catalytic converter cleaner needs, it initially seemed difficult to pick a clear standout. It was tempting to suggest that, with such a low price-point, why not try them all until one works for your needs? However, when we looked at the extremes, we found two winners and one favorite to recommend.

For the budget-conscious user who just wants a quick fix to pass an emissions test, we have to recommend the $ CRC 05063 Guaranteed To Pass Emissions Test Formula. The testament is in the product name and consumer reviews say it does what it claims. Though the price is great, beware if you want to claim the guarantee. Read the box closely. It comes with many hoops and restrictions.

For the long-term-treatment minded (who also happen to have a gasoline engine), we recommend either of the two Cataclean products on the list. By insisting on selling a larger volume of the 120018CAT Cataclean Fuel And Exhaust System Cleaner, the company’s emphasis on long-term treatment is evident. If you do decide to buy the three-liter bottle, be sure to add a funnel to your shopping cart so you can pour it in your tank.

Their 473ml Engine and Catalytic Converter Cleaning Treatment, though it comes in a smaller volume and includes a built-in funnel neck, has just as much emphasis on long-term treatment for results. Though it comes at the highest price point on our list, this emphasis on long-term treatment, which is backed up by customer testimonials, may make it the long-term bargain that many customers are looking for.

Finally, the popularity of Royal Purple Max-Clean Fuel System Cleaner and Stabilizer is a testament to the product’s effectiveness as more than just a catalytic converter cleaner. In this case, the reviews and popularity might say as much about its effectiveness as the product’s labeling claims.

Featured Image by alok rai from Pixabay